Field of the Invention
The present disclosure relates to a motor driving control device for a vehicle.
Related Art
A motor driving control device that controls the rotation of a motor converts a sinusoidal signal into a rectangular wave shaped signal by a circuit such as a comparator or the like, in a case in which, for example, a Hall sensor outputs a sinusoidal signal that corresponds to a magnetic field that varies in accordance with the rotation of the output shaft of the motor. Further, the motor driving control device computes the rotational position of the output shaft by detecting the point where the rectangular wave shaped signal changes from high level to low level or from low level to high level respectively.
A circuit, such as a comparator or the like that converts an analog signal into a digital signal, converts an analog signal into a rectangular wave shaped digital signal by comparing the analog signal with a threshold value having a predetermined voltage value.
Further, also in the controlling of the voltage that is applied to the windings of the motor, the computing section of the motor driving control device computes the duty ratio of the rectangular wave relating to the voltage that is applied to the windings of the motor, by comparing a control voltage and a counter value whose voltage varies at a regular rhythm.
Accordingly, if the potentials of the sensor and the computing section of the motor driving control device are not the same, there is the concern that problems will arise in the operations of the motor driving control device, such as the converting of a sinusoidal signal to a rectangular wave shaped signal, and the computing of the duty ratio of the voltage that is applied to the motor, and the like, cannot be carried out normally, or the like.
Further, there are cases in which the motor driving control device is provided integrally with the motor main body. In such cases, it is desirable for the potential of the motor, at other than the places where voltage is applied such as the windings of the motor or the like, and the potential of the computing section of the motor driving control device, to be the same.
Japanese Patent Application Laid-Open (JP-A) No. 2001-251833 discloses a brushless motor that balances the potentials of the motor other than at the places where voltage is applied, and the potential of the motor driving control device, by electrically connecting a yoke that structures the exterior of the motor, and the output shaft of the motor, and a bearing portion of the output shaft to a ground region of a circuit board.